The congressional investigation into Solyndra has cast a shadow across the solar energy industry, but two new reports show continuing growth in the sector.

A report from the Solar Energy Industries Association finds that grid-connected photovoltaic installation in the U.S. grew 17 percent from the first to second quarter of 2011 and a whopping 69 percent from the second quarter of 2010.

Furthermore, prices continued to plummet as completed module prices dropped 12 percent in the second quarter.

And the initial findings of another report, from the nonprofit Solar Foundation, concludes that the solar industry added 6,735 U.S. jobs between August 2010 and August 2011.

That number does not include jobs created and later lost by companies that failed, such as Solyndra and Evergreen, said Andrea Luecke, the foundation’s executive director.

“We were very conscious and were able to strip them out of our data set,” she said. “We were sort of anticipating that question would come up, given how much attention Solyndra and others are receiving right now.”

Had jobs from Solyndra and other firms been counted, Luecke said, the net number of jobs created would have been closer to 8,000.

Solar now employs more than 100,000 workers domestically, the Solar Foundation census found, a 6.8 percent growth from the same time last year.

The full report will be made available next month.

Solar companies have had to battle recent doubts about the competitiveness of the industry and investigations into the political implications of Solyndra’s collapse, despite good news such as the SEIA report.

“I think when you’re looking at an industry, whether it’s a successful company or a failed company, evaluating it by one company alone is not the way to do it,” said Tom Kimbis, SEIA’s vice president for strategy and external affairs.

The figures from the report continue to indicate that the solar sector as a whole is moving forward as expected. Nonetheless, industry officials are concerned about several upcoming economic and financial roadblocks.

The report singles out the 1603 Treasury grant program, which expires at the end of 2011 and provides an upfront grant in lieu of tax credits a solar installation would accrue over time. It predicts a sudden uptick in new projects as developers rush to meet the December deadline, which requires construction begin by Dec. 31 — just as happened last year, when the 1603 was again threatened with expiration.

Another problem for solar energy going forward is persuading a skeptical public to invest.

“This is sort of, to me, part of the natural evolution of how an industry matures,” Kimbis said. “It’s an education process, right?”